Robots, in particular robotic arms, are often used in manufacturing and assembly plants to perform repetitive functions. The robotic arms often include joints to connect one portion of the robotic arm to another to facilitate the dexterity of the robotic arms and allow for relative movement between the two portions. This commonly includes the use of a rotational joint to move one portion of an arm with respect to another. Springs incorporated into the joint can be used to allow compliance between two portions of the arm. Spring compliance, or deflection, can be measured to determine the torque experienced at the joint.
The task being performed by the robotic arm determines the torque and deflection requirements of the robotic arm. Additionally, the size of the robotic arm is determined by the work which the arm will be used for and size constraints that may be associated with the working environment. The size and the capacity of the torsion spring used in the joint are, therefore, dependent on these factors as well.